Puffed paper imitating felt and process of making the same.



A. L. CLAPP.

PUPFED PAPER IMITATING FELT AND PROCESS OFMAKING THE SAME.

APPLICATION FILED 111112 1911.

1,038,086, I Patented Sept. 10, 1912.

To all wlwm concern:

UNITED STATES PATENT OFFICE.

ALBERT 1;.

CLA'PI, OFZBRAINTREE, MASSACHUSETTS, Assmnon, BY MESNE ASSIGN- Hams, To A. n'non CUTLER, or BOSTON, MASSACHUSETTS.

Terran PAPER mrTATIne FELT AND rnoonss or MAKING Tia-n sum.

Be it lmown that I, ALBERT L. OLAPP, a citizen of'the United States, and a resident of Braintree, in the county of Norfolk and State .of Massachusetts, have invented certain new and useful Improvements in Pulfed Paper Imitating Felt and the Process of Making the Same, of which the following is a s ecification.

have made a peculiar and what believe to be an original'product from sheets of wood pulp, kraft. sulfite pulp and other forms of disintegrated or beaten-out cellulosefibers. This product I have called paper felt or pulfed pulp. In carrying out this process wood pulp, preferably that of a fibrous nature as sulte pulp kraft paper, or kraft pulp in sheet form 1s lmmersed in a strong solution of caustic soda (NaOI-I), about a twenty or I twenty-five per cent. solution being well adapted for the purpose. Care must be taken not to let the sheet remain so long in the solution as to disassociate the'fibers and cause them to fall apart under the strong disintegrating action of the solution, the object being to retain the pulp or fibers in sheet form throughout the process. When the solution is of about the strength above specified the period of immersionmay be about two minutes.

The sheets may be immersed by any suit able means, as by placing them on a wire gauze bed adapted to be lowered into the solution and raised therefrom, or to passably heated. There are, however, many practical ways of drying, it being necessary onl to. surround each sheet with a constant an fresh supply ofair. 'The importance of air drying will be readily seen'from what follows in this description. b

. As the sheet of pulp which is still saturated with the strong soda solution begins to dry, the caustic soda (NaOH) is convert- Specification of Letters latent. Application filed Jul as, 1911. Serial No. 640,505.

Patented se t. 10-, 1912.

ed into sodium carbonate tNa CO due to the absorption of carbon dioxid from the air, and as this absorption increases, the

fibers swell or pufiito many times their natural size. When the chemical action is completed and the sheet is practically'dry, the product has very 'much the appearance and general ropertles of felt, the fibers being suflicient y matted to hold together in the form of a sheet. There still remains throughout the sheet a considerable quantity of alkali in the form of crystals of sodium carbonate which discolors or iinparts a whitish tinge to th'e'sheet and requires removal to render the product commercially useful as asubstitute for felt. This is accomplished by rapidly passing the dried sheet through 'a neutralizing bath of sul-, fur'fc or other suitable acid, a sulfuric acid solution ranging from five to ten percent. bein suitable, and the period of immersion in t e neutralizing bath being relatively brief. It is now necessary to dry the sheet again, but at this stage of the process is not necessary to have so plentiful an air supply as before because there is no further chemical action. When the sheet is finally dried, it still retains the physical appearance of a sheet of felt and may be dyed to any color. 1

The pufiing process is not confined to the use of a'- solution of caustic soda although which are solublein water and will change chemically when exposed to the action of air may be used, :such as sodium sulfite,

pufling or swelling is dependent 'upona sufficient 'supplyof air to cause thefibers to puff .quickly and evenly. .The thickness of the pufled sheet is regulated by the strength of 'the pulfing solution and by the original thickness of-the Sheet.

Figure l'of the accompanying drawing.

this has been found in general practice to be I the most suitable chemical. Other chemicals represents in perspective a sheet which has not been treated; Fig. Qreprescnts in perspective the same sheet pulled in accordance with my invention, the sheet being in creased to several times its original thick ness and its area somewhat decreased.

The texture of the surfaces of the sheet is changed by the process so that the sheet closely resembles felt.

I claim 1. As an article of manufacture a sheet composed of associated wood fibers puffed or increased in diameter, the sheet having a surface texture resembling felt.

2. The process of pufiing and felting wood fibers associated in sheet form, the same consisting in saturating the sheet with a chemical solution having an afiinity for elements of the air, and then subjecting the saturated sheet to contact with air until the fibers are puffed or increased in diameter and the sheet acquires a surface texture resembling felt.

3. The process of pufiing and felting Wood fibers associated in sheet form, the same consisting in saturating the sheet with an alkaline solution having an aflinity for elements of the air, then subjecting the sheet to contact with air until the fibers are pufi'ed or increased in diameter and the sheet acquires a surface texture resembling felt, and finally neutralizing the crystallized alkali.

4. The process of ufiing'and felting wood fibers associated in s ieet form, the same consisting in saturating the sheet with a solution of caustic soda, and then subjecting the saturated sheet to contact with air until the fibers are puffed or increased in diameter and the sheet acquires a surface texture resembling felt.

5. The process of putting and felting wood fibers associated in sheet form, the same consisting in saturating the sheet with a solution of caustic soda, then subjectin the saturated sheet to contact with air untll the fibers are pufi'ed or increased in diameter and the sheet acquires a surface texture resembling felt, and finally subjecting the sheet to a neutralizing bath.

In testimony whereof I have afiixed my signature, in presence of two witnesses.

ALBERT L. CLAPP.

Witnesses:

C. F. BROWN, OTIS M. CARTER. 

